This invention relates to a method and apparatus for detecting overhead transparencies (OHT), such as a dual OHT. Dual overhead transparencies, preferably, have a coating on one side that is compatible with ink jet-type printers and a coating on the other side that is compatible with laser jet-type printers. Such structures of this type, inform the user of the type of OHT.
It is known, in the transparency art, to employ an overhead transparency for color laser printers. Exemplary of such prior art is U.S. Pat. No. 5,939,193 (""193) to B. J. Katsen et al., entitled xe2x80x9cOverhead Transparency for Color Laser Printers and Copiers.xe2x80x9d While the ""193 patent discloses an overhead transparency for color laser printers and copiers, there is no teaching of a dual overhead transparency or dual OHT. Also, the ""193 patent does not disclose a method for detecting the proper side of an OHT.
It is also known, in the transparency art, to employ a dual OHT. Exemplary of such prior art is U.S. Pat. No. 5,030,538 (""538) to R. H. Tobias et al., entitled xe2x80x9cMethod for Producing Overhead Transparencies Having High Color Density Images Using a Double-Sided Image Recording Material.xe2x80x9d While the ""538 reference addresses the deficiencies of the ""193 patent with respect to the use of a dual OHT, the ""538 reference also fails to disclose a method for detecting the proper side of the OHT.
It is apparent from the above that there exists a need in the art for a detection system which is a lightweight through simplicity of parts and uniqueness of structure and which is capable of detecting the proper side of an OHT. It is a purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure.
Generally speaking, this invention fulfills these needs by providing a method for detecting overhead transparencies, comprising the steps of: placing at least one overhead transparency having a first composition into a media tray of the printer; composing a document to be printed; sensing the transparency to determine if the transparency can be printed upon by the printer; placing, if necessary, a transparency having a second composition in the media tray; and printing the document on the transparency having either the first or second composition.
In certain preferred embodiments, the overhead transparency (OHT) can be, but is not limited to, a dual purpose OHT or other suitable print media. Also, the OHT is sensed by a specular and diffuse sensing system. Also, the method includes the step of flipping the OHT so that the proper side of the OHT can be printed upon. Finally, the method includes the step of determining if the OHT is properly oriented.
In another further preferred embodiment, various types of overhead transparencies or other types of media, whether or not the transparencies are dual overhead transparencies, can be detected and the user informed of the transparency available for printing.
The preferred system, according to this invention, offers the following advantages: lightness in weight; ease of assembly and repair; good stability; good durability; excellent economy; and excellent transparency measurement characteristics. In fact, in many of the preferred embodiments, these factors of economy and transparency measurement characteristics are optimized to an extent that is considerably higher than heretofore achieved in prior, known transparency measurement systems.
The above and other features of the present invention, which will become more apparent as a description proceeds, are best understood by considering following detailed description in conjunction with the accompanying drawings, wherein like characters represent like parts throughout the several views and in which: